In this Dec. 27 video frame grab image made from the Iranian broadcaster IRIB TV, U.S. citizen Amir Mirzaei Hekmati, accused by Iran of spying for the CIA, sits in Tehran's revolutionary court, in Iran. Iran's Supreme Court has ordered the retrial of an ex-U.S. Marine who was sentenced to death on charges of working for the CIA.File Photo

Kildee on Sept. 18 wrote a letter to Samantha Power, the permanent U.S. representative to the United Nations, asking her to urge colleagues to consider the issue at the upcoming U.N. General Assembly meeting.

“During the proceedings, I ask that you explore all available opportunities to raise Mr. Hekmati’s case with your colleagues at the U.N.,” Congressman Kildee said in his letter. “I am optimistic that we can facilitate a humanitarian resolution and reunite Mr. Hekmati with his father, mother and sisters soon.”

Recently elected Iranian President Hassan Rouhani is scheduled to visit the U.N. General Assembly next week.

The U.S. does not have formal diplomatic relations with Iran, but Kildee asked Power to encourage colleagues who do have diplomatic relations with the county to “examine all opportunities to facilitate Mr. Hekmati’s release.”

“It is imperative that Mr. Hekmati be reunited with his family so that as the eldest son, he can return to Michigan to care for his ailing father, mother and sisters,” Kildee said in his letter.

Kildee in July sent a letter to Secretary of State John Kerry calling on the U.S. Department of State to prioritize Hekmati's release. The letter was signed and supported by 112 members of Congress.

Hekmati, a former Marine, has been incarcerated since 2011 under suspicion of being an American spy. He was sentenced to death, but an appellate court in Iran overturned his original death sentence because of insufficient evidence.

He spent more than a year in solitary confinement at Tehran's Evin Prison, considered among the world's most brutal prisons. He was in the midst of a two-week visit to Tehran to see his grandmother in August 2011 when he was taken into custody. Iranian officials claimed Amir Hekmati was acting as a spy for the CIA. The Hekmati family and U.S. officials deny the allegation.